3D printing is an emerging manufacturing technology of extruding a material layer by layer to manufacture physical objects based on digital models and is also referred to as additive manufacturing (AM). 3D printing, in which any complex 3D digital models can be input, is suitable for the manufacture of customizable products. In recent years, rapid development of 3D printing technologies has presented many opportunities and challenges to academia and related industries. 3D printing technologies are usually based on a discrete-stacking principle to manufacture the physical objects by extruding a material layer by layer. According to different printing materials and implementation processes, various 3D printing technologies can be divided into five types: (1) high-energy beam sintering and melting molding of a powder or filament material, e.g., selective laser sintering (SLS) and selective laser melting (SLM); (2) photo-curing molding of liquid resin, e.g., stereo lithography appearance (SLA), digital light processing (DLP), etc.; (3) extrusion hot melt molding of wires, e.g., fused deposition modeling (FDM), etc.; (4) bonding or welding molding of sheets/boards/blocks, e.g., Laminated Object Manufacturing (LOM), etc.; and (5) liquid spray printing molding, e.g., three dimensional printing (3DP), etc.
A common 3D printing process includes three-dimensional (3D) digital model generation, data format conversion, slice calculation, printing path planning and 3D printing. The 3D digital model generation is the basis of the entire 3D printing process, and a 3D digital model is generated generally using a variety of 3D modeling software (e.g., CAD software) or 3D scanning equipment. The 3D digital model is subjected to a data format conversion process and then transmitted. Currently, a common data format that is often used in 3D printing is the stereolithography (STL) file format. The slice calculation process is to “cut” the 3D model into slices. In order to materialize the slices generated in the slice calculation process, the path of a print head needs to be planned. The 3D printing material is converted into physical slices during the movement of the print head. Finally, a 3D printer prints (for example, extrudes material) according to the above-mentioned slices and print head path control information, until a complete object is formed.
The path planning is a key step in the overall 3D model printing process. For any topological connected region, the existing path planning methods, such as a Zigzag method, may fill the region using multiple printing paths. Frequent on-off switching of the print head may severely affect the printing quality. On the other hand, the generated printing path may have many corners that are less than or close to 90 degrees, and sharp turns of the print head may seriously affect printing time and printing quality of the printed object.